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PubMed2004

Neutron radiography inspection of investment castings.

Investment casting, also known as the lost wax process, is a manufacturing method employed to produce near net shape metal articles. Traditionally, investment casting has been used to produce structural titanium castings for aero-engine applications with wall thickness less than 1 in (2.54 cm). Recently, airframe manufacturers have been exploring the use of titanium investment casting to replace components traditionally produced from forgings. Use of titanium investment castings for these applications reduces weight, cost, lead time, and part count. Recently, the investment casting process has been selected to produce fracture critical structural titanium airframe components. These airframe components have pushed the traditional inspection techniques to their physical limits due to cross sections on the order of 3 in (7.6 cm). To overcome these inspection limitations, a process incorporating neutron radiography (n-ray) has been developed. In this process, the facecoat of the investment casting mold material contains a cocalcined mixture of yttrium oxide and gadolinium oxide. The presence of the gadolinium oxide, allows for neutron radiographic imaging (and eventual removal and repair) of mold facecoat inclusions that remain within these thick cross sectional castings. Probability of detection (POD) studies have shown a 3 x improvement of detecting a 0.050 x 0.007 in2 (1.270 x 0.178 mm2) inclusion of this cocalcined material using n-ray techniques when compared to the POD using traditional X-ray techniques. Further, it has been shown that this n-ray compatible mold facecoat material produces titanium castings of equal metallurgical quality when compared to the traditional materials. Since investment castings can be very large and heavy, the neutron radiography facilities at the University of California, Davis McClellan Nuclear Radiation Center (UCD/MNRC) were used to develop the inspection techniques. The UCD/MNRC has very unique facilities that can handle large parts up to 39 ft (12 m) in length and 13 ft (4 m) high weighing up to 5000 lbs (2300 kg). These handling systems are robotically driven. The neutron radiographic system consists of a highly thermalized neutron beam. The neutron beam has an intensity of 5.6 x 10(6) n/cm2 s, with a L/D = 200 at a power of 2 MW. A divergent beam collimator is used which provides a beam of approximately 22 in (56 cm) in diameter at the film plane. A vacuum cassette with a gadolinium vapor deposited screen is used to collect the image. Exposure times can be as short as 3 min, or up to 30 min.

Journal Article↗
PubMed2001

Kinetics of initiation, propagation, and termination for the [rac-(C(2)H(4)(1-indenyl)(2))ZrMe][MeB(C(6)F(5))(3)]-catalyzed polymerization of 1-hexene.

Metallocene-catalyzed polymerization of 1-alkenes offers fine control of critical polymer attributes such as molecular weight, polydispersity, tacticity, and comonomer incorporation. Enormous effort has been expended on the synthesis and discovery of new catalysts and activators, but elementary aspects of the catalytic processes remain unclear. For example, it is unclear how the catalyst is distributed among active and dormant sites and how this distribution influences the order in monomer for the propagation rates, for which widely varying values are reported. Similarly, although empirical relationships between average molecular weights and monomer have been established for many systems, the underlying mechanisms of chain termination are unclear. Another area of intense interest concerns the role of ion-pairing in controlling the activity and termination mechanisms of metallocene-catalyzed polymerizations. Herein we report the application of quenched-flow kinetics, active site counting, polymer microstructure analysis, and molecular weight distribution analysis to the determination of fundamental rate laws for initiation, propagation, and termination for the polymerization of 1-hexene in toluene solution as catalyzed by the contact ion-pair, [rac-(C(2)H(4)(1-indenyl)(2))ZrMe][MeB(C(6)F(5))(3)] (1) over the temperature range of -10 to 50 degrees C. Highly isotactic (>99% mmmm) poly-1-hexene is produced with no apparent enchained regioerrors. Initiation and propagation processes are first order in the concentrations of 1-hexene and 1 but independent of excess borane or the addition of the contact ion-pair [PhNMe(3)][MeB(C(6)F(5))(3)]. Active site counting and the reaction kinetics provide no evidence of catalyst accumulation in dormant or inactive sites. Initiation is slower than propagation by a factor of 70. The principal termination process is the formation of unsaturates of two types: vinylidene end groups that arise from termination after a 1,2 insertion and vinylene end groups that follow 2,1 insertions. The rate law for the former termination process is independent of the 1-hexene concentration, whereas the latter is first order. Analysis of (13)C-labeled polymer provides support for a mechanism of vinylene end group formation that is not chain transfer to monomer. Deterministic modeling of the molecular weight distributions using the fundamental rate laws and kinetic constants demonstrates the robustness of the kinetic analysis. Comparisons of insertion frequencies with estimated limits on the rates of ion-pair symmetrization obtained by NMR suggest that ion-pair separation prior to insertion is not required, but the analysis requires assumptions that cannot be validated.

Alkenes↗
PubMed2000

Use of bioelectrical impedance techniques for monitoring nutritional status in patients on maintenance dialysis.

Malnutrition continues to be an important correlate of survival in dialysis patients. Nutritional surveillance at the clinical level requires use of simple, reasonably accurate, and easily accessible techniques for multicompartmental body composition analysis. Unfortunately, although gold standard methodologies (body density by underwater weight, total body water by isotope dilution, bone mineral content by neutron activation, total body potassium by (40)K whole body gamma counting) provide very precise assessments, they are not applicable to routine clinical practice. Because of its availability and simplicity, bioelectrical impedance (BEI) has significant potential as a complement to standard anthropometric techniques in the nutritional monitoring of patients with chronic renal failure. Consistency of technique and standardization of BEI equipment are essential for reproducibility of results. Several studies have validated the use of total body water by BEI as a surrogate for isotope dilution methods in dialysis patients, whereas others have established an excellent correlation with the volume of distribution of urea as measured by urea kinetic volume. Bioimpedance analysis for measurement of lean body mass has been extensively evaluated in stable healthy populations, with results similar to those obtained using hydrodensitometry and total body potassium. In dialysis patients, accuracy is contingent on a stable hydration status and/or appropriate correction for changes in extracellular volume status over time. Recent publication of bioimpedance norms for the hemodialysis population allows better comparisons with the national reference population studied as part of the National Health and Nutrition Examination Survey III (US Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Health Statistics, Hyattsville, MD). BEI methodology is a practical bedside tool for assessment of body composition that provides more consistent and reproducible results than standard anthropometry alone.

Anthropometry↗
PubMed1996

Time-related induction of DNA repair synthesis in rat hepatocytes following in vivo treatment with cyproterone acetate.

Cyproterone acetate (CPA), a synthetic steroid hormone widely used as a human pharmaceutical, has recently been shown to induce unscheduled DNA synthesis (UDS) in vitro in primary cultures of rat and human hepatocytes. In the present study CPA was evaluated for its ability to initiate UDS in the liver of female rats in vivo by means of the in vivo/in vitro hepatocyte DNA repair test. Using the standard sampling time of 16 h after single oral dosing, a dose-related UDS response at >50 mg CPA/kg body wt was observed. In order to examine the time course of CPA-induced UDS, different sampling times (4, 16, 48, 72, 96 and 144 h) after a single oral administration of 100 mg CPA/kg body wt were used. Whereas no UDS was induced in liver cells isolated 4 h after treatment, continuous DNA repair activity was observed after 16 h, with a maximum effect of approximately 10 net nuclear grains on day 4 after dosing. After a post-application period of 6 days the net grain counts returned to near control level. In contrast to the data with CPA, DNA damage induced by the positive control compound 2-acetylaminofluorene was removed much faster, within 2 days after administration. The time course of UDS activity during the first 4 days after administration of CPA parallels the previously reported time course of DNA adduct formation. However, a subsequent decrease and final cessation of UDS on day 6 takes place, although significant levels of CPA-DNA adducts have been reported to occur at that time point in rat liver cells. Whereas the time-related onset of UDS is suggested to reflect the pharmacokinetics of the activation of CPA to DNA-reactive intermediates, it remains unclear why the excision repair of DNA adducts did not continue. In addition to DNA repair synthesis, CPA was also shown to clearly increase the incidence of S phase cells under the test conditions applied, confirming the known mitogenic potential of CPA in rat liver.

Androgen Antagonists↗
PubMed1999

Estimation of offspring production from a limited number of stage-structured censuses.

We propose a procedure for maximum likelihood estimation of the number of animals or offspring in a closed population where the individuals counted go through stages or age-groups. Application of the procedure requires knowledge of the distributions of the stage durations. A procedure for maximum likelihood estimation of those based on marked animals is also given. The procedures are illustrated by applying them to gray seal (Halichoerus grypus) data from Froan Nature Reserve, Central Norway, from the breeding seasons 1990-1999.

Animals↗
PubMed2002

CSF evaluation in primary CNS lymphoma patients by PCR of the CDR III IgH genes.

BACKGROUND: Cytologic evaluation of CSF does not consistently detect malignant cells in patients with primary CNS lymphoma (PCNSL). The potentially more sensitive molecular assessment of monoclonality has not been shown in CSF samples. METHODS: The authors studied nested PCR of the complementary determining region III (CDR III) on 76 CSF specimens of patients with PCNSL. Patients with systemic disseminated B-cell non-Hodgkin's lymphoma (n = 17) and 17 patients with no history of lymphoma were compared. PCR products were evaluated by automated fluorescent fragment analysis (ALF). RESULTS: In 68 patients with PCNSL, the authors analyzed the first obtained CSF sample. Nevertheless, 60 patients were taking corticosteroids. In 16 PCNSL samples, amplifiable DNA was not yielded. Taking into account that at least two independent assays have to be performed, CDR III PCR consistently revealed monoclonal products in eight PCNSL and polyclonal results in 52 PCNSL specimens. CDR III PCR detected no monoclonal PCR products in patients without history of lymphoma. In 10 patients with PCNSL, the PCR result and the CSF cytology were discordant. Concerning therapeutic impact, leptomeningeal tumor spread did not predict tumor response in this group of patients with PCNSL. CONCLUSIONS: This study performed CDR III PCR as a routine diagnostic technique applicable even on CSF samples with low cell counts. These data present low incidence of leptomeningeal involvement in this subset of pretreated PCNSL patients. Because the CSF evaluation did not predict outcome in our patients, further analysis in patients with PCNSL should focus on CSF samples that are obtained very early after diagnosis.

Adult↗
PubMed2003

Photon counting with a loop detector.

We propose a design for a photon-counting detector that is capable of resolving multiphoton events. The basic element of the setup is a fiber loop, which traps the input field with the help of a fast electro-optic switch. A single weakly coupled avalanche photodiode is used to detect small portions of the signal field extracted from the loop. We analyze the response of the loop detector to an arbitrary input field and discuss both the reconstruction of the photon-number distribution of an unknown field from the count statistics measured in the setup and the application of the detector in conditional-state preparation.

Journal Article↗
PubMed2006

Use of statistics in plant biotechnology.

Statistics and experimental design are important tools for the plant biotechnologist and should be used when planning and conducting experiments as well as during the analysis and interpretation of results. This chapter provides some basic concepts important to the statistical analysis of data obtained from plant tissue culture or biotechnological experiments, and illustrates the application of common statistical procedures to analyze binomial, count, and continuous data for experiments with different treatment factors as well as identifying trends of dosage treatment factors.

Analysis of Variance↗
PubMed2002

The effect of spermine on plasmid condensation and dye release observed by fluorescence correlation spectroscopy.

We demonstrate that fluorescence correlation spectroscopy (FCS) can be employed to follow the conformational changes of DNA molecules induced by the addition of a cationic condensing compound (spermine). In our experiments the plasmid pHbetaAPr-1-neo (10 kbp; contour length 3.4 microm) was labeled with propidium iodide (PrIo) and then titrated with spermine to induce its condensation. When spermine was applied at concentrations above 5 microM (spermine/DNAphosphate=0.375), the diffusion time of the labeled plasmid dropped from 15 ms down to 3 ms (its diffusion coefficient, D, increased from 1.0x10(-12) m2/s to 6.0x10(-12) m2/s). The application of spermine was also accompanied by decreasing count rate and particle number, reflecting the dye's dissociation. The data presented show that FCS may become a valuable tool in studying supramolecular aggregate formation, especially when association is followed by a change in the hydrodynamic size of the resulting complex.

DNA↗
PubMed2003

Off-pump coronary artery bypass surgery is associated with reduced neutrophil activation as measured by the expression of CD11b: a prospective randomized study.

BACKGROUND: Coronary artery bypass grafting (CABG) surgery is associated with systemic inflammation. Activation of neutrophils is a crucial step in inflammation and results in neutrophil sequestration within the tissues. One of the potential advantages of performing off-pump coronary artery bypass (OPCAB) surgery is the attenuation of the systemic inflammatory response. This prospective randomized study compares neutrophil activation in patients undergoing OPCAB versus those undergoing CABG with cardiopulmonary bypass (CPB). METHODS: Twenty patients undergoing primary isolated CABG were randomly divided prospectively into 2 groups: 1 group underwent CABG with CPB, and the other group underwent OPCAB. Central venous blood samples were obtained before skin incision and at 15 minutes, 60 minutes, 2 hours, 5 hours, and 24 hours following the initiation of CPB or application of the stabilization device. Differential white cell counts were measured with routine laboratory techniques. CD11b surface expression on neutrophils was measured by flow cytometry. Interleukin 8 levels in the plasma were measured by enzyme-linked immunosorbent assays. RESULTS: The 2 groups were matched with respect to preoperative and operative characteristics. White cell and neutrophil counts rose in both groups following the operation but were significantly higher in the OPCAB group at 5 hours (P < .001 and P = .002, respectively). Interleukin 8 concentrations were significantly higher in the CPB group at 5 hours following the initiation of CPB (P = .034). CD11b levels were significantly higher in the CPB group at 60 minutes (P = .002). CONCLUSION: This prospective randomized study demonstrates that the activation of circulating neutrophils as measured by CD11b expression is lower following OPCAB than in CPB. Although OPCAB is associated with significantly higher neutrophil counts, these neutrophils exhibit fewer activation markers. The lower postoperative neutrophil counts occurring in the CPB group may be explained by the activation and consequent sequestration of the neutrophils in the CPB circuit and tissues.

Aged↗
PubMed1989

Idiopathic thrombocytopenic purpura (ITP): immunomodulation by intravenous immunoglobulin (IVIg).

ITP is a destructive thrombocytopenia. Platelets are coated with antibodies and these opsonized platelets are rapidly removed by phagocytes. On the other hand, therapeutic application of antibody concentrates (IVIg) rapidly raise platelet counts, and in some patients, sustained platelet recovery has been observed. The mechanism of action of IVIg is far from being clear. Several possible mechanism of action of IVIg treatment have been described. The immediate effect of IVIg seems to be a decrease in (unspecific) Fc mediated mononuclear phagocytosis, the long term effect might be a change in the complex network of the regulatory function of the immune response. Both types of interactions seem to play a keyrole in the immunomodulation. The various possible modes of actions evoke investigation of IVIg in a wide range of diseases with similar ineffective immune response. Controlled clinical studies have to be done to prove or disapprove the use of IVIg in other indications.

Autoimmune Diseases↗
PubMedDate not supplied

Liver, spleen and tumor volume measured by personal computer.

BACKGROUND/AIMS: Computed tomography (CT) scans are common examinations for patients with chronic liver diseases. To quantitate the organ or tumor volume from the scans and to accomplish the task in an efficient way with the most economic equipment, we developed a system based on a personal computer. METHODOLOGY: We used color-markers and transparency to sketch the edges of liver, hepatoma, and spleen. Each organ or tumor of interest is marked out by fine-point markers on pieces of transparency. The sketch was scanned into a digitized image format on a personal computer (Pentium 133). The calculation involves edge detection, three-dimensional reconstruction, and voxel counting. By using summation-of-the-area and trapezoid approximation technique, the voxels of each structure are counted. In this study, we illustrate the potential application in the management of a hepatic cancer patient. RESULTS: After digitalization, the data size of CT images is about 1 to 1.5 megabytes. It takes less than 5 min to complete volume calculation. CONCLUSIONS: By this method, tumor load before and after chemotherapy can be estimated easily and accurately. This would be helpful in clinical practice.

Carcinoma, Hepatocellular↗
PubMed2000

Methoprene tolerance in Aedes nigromaculis in Fresno County, California.

Methoprene, a juvenile hormone analogue, has been used for at least 20 years as the primary insecticide to control the pasture mosquito Aedes nigromaculis in Fresno County, California. First reports of apparent methoprene control failures were noted in a pasture west of Fresno in September 1998. Insufficient control was noted in 12 different pastures the following season from April to September 1999. In September of 1999, field trials were conducted to better ascertain the level of control. Results based on pupal counts from different methoprene formulations and rates of application indicated that in some pastures low levels of control were achieved with Altosid (Liquid Larvicide) and Altosid XR-G. Control with Altosid Pellets was reported at 52-99%.

Aedes↗
PubMed1992

[Flow karyotyping and chromosome sorting].

For flow karyotyping and sorting, chromosomes are stained in suspension with appropriate DNA fluorochromes, and passed singly through a beam of laser light. The emitted pulses of fluorescence and scattered light are measured and stored in the form of a histogram displaying the number of pulses versus fluorescence or scattered light intensity. A data processing system was devised to remove signals from cell debris or chromosome fragments. A selective window was set in a dot plot of fluorescence versus scattered light intensities and a program was made to count pulses from the gated area only. As application of chromosome fractionation, flow cytometry has been used for karyotype analysis, gene mapping, and chromosomal DNA library construction.

Chromosome Mapping↗
PubMed1992

[Myocardial perfusion and clearance of 99mTc teboroxime assessed by SPECT].

99mTc teboroxime is a new myocardial imaging agent that has characteristics of high accumulation in the heart and rapid clearance. We performed tomographic teboroxime study and compared the findings with that of 201Tl. Myocardial teboroxime clearance was calculated by dynamic single photon emission computed tomography (SPECT) using continuous repetitive rotation acquisition method. Teboroxime SPECT image was reconstructed by the three-minute data started from 4 minutes after injection. In 45 myocardial regions (15 patients), complete agreement between 201Tl and 99mTc teboroxime was obtained in 33 regions (73%), when the findings were classified as normal, ischemia and infarction. Significant delay in clearance was seen in the region of coronary stenosis (greater than or equal to 75%) compared with that in the control region (p = 0.0087 at rest, and p = 0.0385 at peak exercise by paired T test). Septum-to-lateral ratios of the clearance and myocardial initial count showed positive correlation (r = 0.743). Further clinical application of this radiopharmaceutical is expected as a new myocardial imaging agent.

Coronary Circulation↗
PubMed1991

[Study on serum neopterin concentration in hemophiliacs with anti-human immunodeficiency-virus type I antibody].

The present study was undertaken to discuss whether measurement of neopterin (NP) released into blood from monocytes/macrophage following activation of lymphocytes were useful tool to predict development of AIDS after HIV-1 infection. The subjects used for this study were eighty one cases of hemophilia, of whom 47 cases were HIV-1 antibody tested positive. Serum NP concentration (15.0 +/- 13.8 nmol/l) in anti-HIV-1 antibody-positive group was higher than in-negative group (5.7 +/- 3.3 nmol/l) (p less than 0.05), in which there was no case whose serum NP level amounted to more than 20 nmol/l. In anti-HIV-1 antibody-positive group, in which CD4/CD8 lymphocyte ratio was less than 0.4, serum NP level was significantly higher than in the group whose lymphocyte ratio was more than 0.5 (p less than 0.05). This result represents that there is a reverse correlation of NP concentration with the developing level of immunodeficiency. Furthermore, in eight cases who developed AIDS, serum NP levels turned to increase from several months or earlier until in all cases the levels were more than 30 nmol/l. In three cases of five who were dead, serum NP concentration had decreased to death since several months through one year. These findings reveal that measurement of serum NP concentration is correlated with clinical outcome after HIV-1 infection and it is useful as the marker for prediction of AIDS development. Also these findings represent that a parallel application of serum NP assay to CD4 lymphocyte counting, detection of anti-HIV-1 antibody, IgA, beta 2-microglobulin assays can predict the outcome of the HIV-1 infection more precisely.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Influence of cloprostenol-15-glycal on some hematologic values.

Cloprostenol-15-glycal is an analog of natural prostaglandin F2 alpha. It is prepared fully synthetically and is a basic substance of the veterinary medicament of firm name Glystrofan (chem. conc. Spolana, Neratovice, CSR). The effect of this substance was studied after intravenous application in double concentration on the blood cell count in experiment on rats. A significant decrease of erythrocyte count was observed in late sampling intervals especially after higher dose. A temporary elevation of leucocyte count occurred in white blood cell series. There was lymphocyte count elevation, while neutrophil count decreased. In the course of experiment a decrease of thrombocyte count occurred, especially after higher dose. Characteristic of described changes corresponds to that, which was observed by prostaglandins of series E. Changes in perifery blood cell count can be in agreement with the effect of cloprostenol-15-glycal on the production or influence of growth factors and on the proliferation of pluripotent hematogenic cells respectively.

Animals↗